


Math Problem

by Skinner (psiten)



Series: Serious [8]
Category: Tennis no Oujisama | Prince of Tennis
Genre: Child, Future Fic, M/M, Original Character(s), probability and statistics, prompt
Language: English
Status: Completed
Published: 2011-07-05
Updated: 2011-07-05
Packaged: 2017-10-21 01:23:33
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,515
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/219341
Author URL: https://archiveofourown.org/users/psiten/pseuds/Skinner
Summary: <blockquote class="userstuff">
              <blockquote>
<br/><i>Mitsu tore three strips off the scrap paper and folded them in half. "Draw a goat in two, and a bicycle in one. Don't show me which."</i>
<br/></blockquote><p>Teaching their son math is Tezuka's problem -- Fuji insists. But sometimes, a little cooperation is required.</p>
            </blockquote>





	Math Problem

**Author's Note:**

  * For [Tacuma](https://archiveofourown.org/users/Tacuma/gifts).



> In response to the quote prompt, "I have not failed. I've just found 10,000 ways that won't work."

     It was easy to spot when Mitsu was sulking. He sat up slightly straighter in his chair, clenched his toes, and held his book in his right hand rather than his left. The lines tracing his cheeks and eyes now that forty had come and gone furrowed so slightly more, lending him a sternness that rivaled his grandfather's. And he'd never say what was bothering him. If he was only sulking, and not properly upset, he'd never think it worth mentioning.

     Fuji traced a few strands of rich, brown hair going to salt-and-pepper over his lover's ear. Mitsu had always looked like a dignified older man, and it suited him. Fuji had been secretly thrilled beyond measure when he'd heard the uncompromising voice of the man he adored, echoing across the hair stylists' shop, explaining that he had absolutely no intention of covering his gray with dye. In a few years, he'd be downright venerable.

     "Dinner will be a few more minutes," he whispered. "Would you like some tea?"

     His captain marked his place in the book he'd been studying and took Fuji's hand in his own. "I'm fine. Thank you." His profile as Mitsu glanced at their son, working more diligently on his homework than Fuji ever had, said everything he needed to know. "Maybe you could help Kenji with his studies. He has a tricky probability question--"

     "--and you're having another failure to communicate?" He had yet to meet a Tezuka father who could talk to his son about anything beyond the weather without temperaments clashing and tempers flaring, just like he had yet to meet a Tezuka who didn't dote on his grandchild to distraction. But Fuji had no intention of waiting another twenty years to see their relationship patched up the same way Kenji's birth had mellowed Mitsu's father, Kuniharu.

     And his lover wouldn't give up. He didn't need to promise for Fuji to know that. He only had to sigh in the way he did now and stand up with that firm set to his chin. "I have not failed. I've just found 10,000 ways that won't work."

     "All right, then." With a smile, Fuji stood up on his toes to kiss the silly, stubborn man on the cheek. "I'll see what I can do."

     Waiting for Mitsu to disappear into the kitchen, he watched their son a little longer. Kenji was ignoring the calculator, tapping his pencil along his paper in a line -- one, two, three, then starting over again -- with a child's echo of the hard stare that had made his father so popular with the ladies (and young men) in school. That'd be his little heartbreaker someday. Although, unlike the stern Seigaku tennis captain, he'd probably know exactly what he was doing. He had a bit of a Fuji's sensibility underneath the uncrackable Tezuka shell.

     "So, how's my little man doing?"

     "I detest goats," Kenji grumbled immediately, "and I will never participate in a game show that employs them. Why can't I tell the teacher that there's no point in knowing the chance that I'll pick a door with a bicycle instead of a goat because a professional Go player doesn't need to depend on game shows to own a bike? It's a valid answer."

     He was simply precious when he insisted on being perverse. "And you think you'll never have to consider the probability of where your opponent will play a stone?"

     "There are no goats in Go."

     So serious and so absolute. Just like _someone else_ he knew, Fuji thought to himself, messing up his son's hair. "But there is a 'go' in goat!"

     Kenji narrowed his eyes in an adorable little glare that Fuji was sure would grow intimidating in time. "Dad..."

     "Your father is much better at mathematics than I am. I won't be any help to you."

     "Because you don't want to. You could."

     It was true, he could. He remembered this problem from his own fourth grade math class, and he could probably recite the explanation his sister had given. But he'd made absolutely no promises that he'd help _with the math_. Mitsu really needed to do better. "You can bring me all your problems with English or literature or anything else. Your father can give you a more detailed explanation for math."

     "Father never does anything but saying, ' _Do it right_ ,' or telling me the answer like it's obvious," their son answered back with a scowl. "I can't learn from that." But after half a minute of staring back at Fuji's silent, unchanging grin, he rolled his eyes and marched over to the kitchen. "Father, can you help? Dad's being diffi--"

     " _Kenji_."

     Eiji was absolutely right about the boy having an attitude, but Fuji wouldn't have wanted it any other way. No more than he would have wanted Mitsu to give him fewer laps to run when he'd crossed the line in middle school. It was enough that they both had learned to swallow their pride when they were wrong. "Dad looked at the problem, and he said I should ask you."

     "Then I'll do what I can."

     His lover followed their son to the table, a touch of nervousness showing in the way he knit his fingers. "So," Kenji sighed, "the problem says a television host puts two goats and one bicycle behind three doors. You want the bicycle. After you pick a door, he shows you that one of the other doors has a goat, then asks if you want to switch. I have to answer yes or no, and say why, and the teacher says, 'It doesn't matter,' is the wrong answer." The fourth grader turned the same accusing glare on his father that he'd been giving the worksheet earlier. "But it's one goat or one bike, a fifty-fifty chance either way. It _doesn't_ matter."

     "But the one-third chance of--"

     Fuji cut Mitsu off with a cough and whispered in his ear as he excused himself from the table. "I think he wants the right question, dear. Not the right answer."

     The fullsized Tezuka and the miniature Tezuka stared at each other with blank, pure intensity, in that way that always made Fuji want to die laughing. They kept it up until he'd walked all the way to the kitchen, where he peeked around the corner to watch from safely out of the way.

     "Why... would you say fifty-fifty?"

     Their son raised an incredulous eyebrow. "Because you've got two things and two doors. The chance of finding the bike is obviously one in two."

     Mitsu tore three strips off the scrap paper and folded them in half. "Draw a goat in two, and a bicycle in one. Don't show me which," he ordered, and without a word (but with a scowl) Kenji did as he was told. When the child finished scribbling, he lined them up in front of his father, who pointed to the one in the middle. "What's the chance that the bicycle is here?"

     "One in three, sir."

     "And that a goat is here?"

     "Two in three, sir."

     "Good. Continue." Again with a sullen silence, Kenji lifted the flap on the third paper, and Mitsu nodded. "Now, the chance that the center is the bicycle... That is, the chance that you put the bicycle in the center..."

     He could hear the words ' _...hasn't changed_ ' hanging on his lover's sentence, like a leaf clinging to a branch in a fierce wind. Fuji had to bite his own tongue to keep from calling out, ' _Don't say it!_ '

     After a long pause, Mitsu finished with a rather awkward, "... is what?" It was horribly difficult to keep from applauding at his gallant effort.

     Kenji's eyes blinked wide. "The chance that I put it there? One in three, sir, but that's for all the doors. A one-third chance can't disappear from the problem when I open the last one."

     "No, it can't." Every trace of sulk gone from his demeanor, Mitsu pushed away from the table. "When you find where it went, tell me your answer. I expect you to finish here and clear the table before dinnertime."

     "Yes, sir." This time, Kenji didn't sound like he was answering back. He was too busy making a new diagram on his worksheet. "Actually, I think I've got it."

     Peeking over their son's shoulder, Mitsu nodded and patted the boy on the back. "Good job."

     By the time his lover made it to the kitchen with his heavy sighs and his tight embrace, Fuji was back at the counter getting the rice ready to serve, innocently pretending he hadn't been watching the whole thing. The kiss on his neck and the whisper in his ear knew exactly how innocent he wasn't, of course.

     "Have I mentioned that I love you, Syuusuke?"

     "You're allowed to say it again." He held Mitsu's arms where they circled his waist, giving their son the time he needed to finish shuffling his notebooks back into his schoolbag. "Now we have to find 10,000 more ways that work, and we might just survive his adolescence."


End file.
